memstream delete -> stream delete (18)

Use mz_stream_delete instead of mz_stream_mem_delete.
diff --git a/mz_zip_rw.c b/mz_zip_rw.c
index 646869d..c2ce823 100644
--- a/mz_zip_rw.c
+++ b/mz_zip_rw.c
@@ -211,8 +211,8 @@
         mz_stream_os_delete(&reader->file_stream);
 
     if (reader->mem_stream != NULL) {
-        mz_stream_mem_close(reader->mem_stream);
-        mz_stream_mem_delete(&reader->mem_stream);
+        mz_stream_close(reader->mem_stream);
+        mz_stream_delete(&reader->mem_stream);
     }
 
     return err;